dolfin team mailing list archive

[Martin Sandve Alnæs <martinal@xxxxxxxxx>]

On 17 June 2011 15:20, Garth N. Wells <gnw20@xxxxxxxxx> wrote:
>
>
> On 17/06/11 14:05, Martin Sandve Alnęs wrote:
>> On 17 June 2011 12:17, Garth N. Wells <gnw20@xxxxxxxxx> wrote:
>>>
>>>
>>> On 17/06/11 11:04, Anders Logg wrote:
>>>> On Fri, Jun 17, 2011 at 10:49:47AM +0100, Garth N. Wells wrote:
>>>>>
>>>>>
>>>>> On 17/06/11 10:43, Anders Logg wrote:
>>>>>> On Fri, Jun 17, 2011 at 10:33:23AM +0100, Garth N. Wells wrote:
>>>>>>>
>>>>>>>
>>>>>>> On 17/06/11 10:28, Anders Logg wrote:
>>>>>>>> On Fri, Jun 17, 2011 at 11:24:21AM +0200, Marie E. Rognes wrote:
>>>>>>>>>
>>>>>>>>> On 17. juni 2011, at 11:05, "Garth N. Wells" <gnw20@xxxxxxxxx> wrote:
>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> On 17/06/11 09:34, Anders Logg wrote:
>>>>>>>>>>> On Fri, Jun 17, 2011 at 08:46:46AM +0100, Garth N. Wells wrote:
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> On 17/06/11 08:35, Garth N. Wells wrote:
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>> On 12/06/11 21:36, Anders Logg wrote:
>>>>>>>>>>>>>> On Fri, Jun 10, 2011 at 10:33:41PM +0100, Florian Rathgeber wrote:
>>>>>>>>>>>>>> On 11/05/11 15:43, Anders Logg wrote:
>>>>>>>>>>>>>>>>> On Wed, May 11, 2011 at 03:57:52PM +0200, Anders Logg wrote:
>>>>>>>>>>>>>>>>>> On Tue, May 10, 2011 at 10:57:07PM +0200, Martin Sandve Alnęs wrote:
>>>>>>>>>>>>>>>>>>> On 10 May 2011 17:52, Anders Logg <logg@xxxxxxxxx> wrote:
>>>>>>>>>>>>>>>>>>>> On Tue, May 10, 2011 at 03:49:18PM +0200, Martin Sandve Alnęs wrote:
>>>>>>>>>>>>>>>>>>>>> On 3 May 2011 18:25, Johannes Ring <johannr@xxxxxxxxx> wrote:
>>>>>>>>>>>>>>>>>>>>>> On Tue, May 3, 2011 at 3:52 PM, Anders Logg <logg@xxxxxxxxx> wrote:
>>>>>>>>>>>>>>>>>>>>>>> It happens to me a lot. Johannes has tried to explain to me why it
>>>>>>>>>>>>>>>>>>>>>>> happens a number of times but I still don't understand why.
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> Maybe he can try to explain it again to you and then I might also
>>>>>>>>>>>>>>>>>>>>>>> understand. :-)
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> I think I just bring up the following instructions (which I think looks good):
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> http://wiki.squid-cache.org/BzrInstructions
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> Thanks Johannes.
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> Basically the problem is that bazaar numbers commits with contiguous
>>>>>>>>>>>>>>>>>>>>> integers, and when Bob and Alice works locally they will get the same
>>>>>>>>>>>>>>>>>>>>> commit ids for different commits. When you stand in branch Alice and
>>>>>>>>>>>>>>>>>>>>> merge from branch Bob, the commit numbers of branch Alice are
>>>>>>>>>>>>>>>>>>>>> conserved and a single new merge commit is recorded on top there. The
>>>>>>>>>>>>>>>>>>>>> commit numbers from branch Bob are lost in the merge. Therefore, to
>>>>>>>>>>>>>>>>>>>>> conserve the commit ids in the central branch, you have to merge from
>>>>>>>>>>>>>>>>>>>>> your own branch into the server branch, not the other way around.
>>>>>>>>>>>>>>>>>>>>> Otherwise we can never safely use the commit revisions from the
>>>>>>>>>>>>>>>>>>>>> central branch, since they may change every time somebody merges the
>>>>>>>>>>>>>>>>>>>>> 'wrong way'.
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> This problem does not occur with hg or git, because they use a hash
>>>>>>>>>>>>>>>>>>>>> value to identify a each commit.
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> So if I'm Bob and Alice has pushed some changes to the main branch
>>>>>>>>>>>>>>>>>>>> before me, which exact commands should I write?
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> Depends on how you set up your repositories, where your branches are
>>>>>>>>>>>>>>>>>>> located, etc...
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> You really have to read up on it and try it out a bit to understand
>>>>>>>>>>>>>>>>>>> it, and I doubt I can write it better than what Johannes linked to +
>>>>>>>>>>>>>>>>>>> the bazaar docs.
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> I plan to keep a local repository with multiple branches like this:
>>>>>>>>>>>>>>>>>>>  ~/dev/fenics/ufl/ - local ufl repository
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> Is this a repository? Or is it just a directory named ufl inside which
>>>>>>>>>>>>>>>>>> you keep a number of different repositories?
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> Talked to Martin during lunch. Here's a simple summary of what needs
>>>>>>>>>>>>>>>>> to be done to set things up correctly (Cc to dolfin-dev so everyone else
>>>>>>>>>>>>>>>>> sees this):
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>  bzr init-repo foo
>>>>>>>>>>>>>>>>>  cd foo
>>>>>>>>>>>>>>>>>  bzr checkout lp:foo trunk
>>>>>>>>>>>>>>>>>  bzr branch trunk work
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> We should add this to the developer page in the documentation.
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> Everyone should adopt this and we should pick on anyone that pushes
>>>>>>>>>>>>>>>>> removed changesets.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> There's an effective way to make these pushes impossible and disable the
>>>>>>>>>>>>>> bzr "feature" of renumbering revisions: set the option
>>>>>>>>>>>>>> append_revisions_only=True in <yourbranch>/.bzr/branch/branch.conf
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> For branches on launchpad this works as follows:
>>>>>>>>>>>>>> 1) sftp bazaar.launchpad.net
>>>>>>>>>>>>>>     cd ~user/project/branch/.bzr/branch
>>>>>>>>>>>>>>     get branch.conf
>>>>>>>>>>>>>> 2) edit the downloaded file, adding append_revisions_only = True
>>>>>>>>>>>>>> 3)   put branch.conf
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> I suggest doing this for all branches on launchpad to enforce consistent
>>>>>>>>>>>>>> revision numbers.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> More background: http://stackoverflow.com/questions/5413602
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Thanks. I've fixed this now for DOLFIN, FFC, UFL, UFC, FIAT.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>> Could you please undo this. I can't push changes from my personal branch
>>>>>>>>>>>>> to DOLFIN. I don't see that this change has any use. (If we want cvs,
>>>>>>>>>>>>> then we should use cvs.)
>>>>>>>>>>>>>
>>>>>>>>>>>>> I've tried to follow the instructions to undo the change, but can't get
>>>>>>>>>>>>> it to work.
>>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> I've undone this for DOLFIN so I could push my changes.
>>>>>>>>>>>
>>>>>>>>>>> You should have figured out how to do the merge properly instead. We
>>>>>>>>>>> should add it back to force everyone to learn how to use bzr. ;-)
>>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> Merge is 'bzr merge xxx'. That's a proper merge.
>>>>>>>>>>
>>>>>>>>>>> The point is to not rewrite history for the common repo. This is not
>>>>>>>>>>> the same as cvs. It's still distributed but it means merges have to be
>>>>>>>>>>> done more carefully.
>>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> There is no history re-writing. It's just adding changesets. Unique
>>>>>>>>>> changeset numbering that bzr does will always be problematic with
>>>>>>>>>> distributed version control. If you want a unique identifier, use the
>>>>>>>>>> revision id.
>>>>>>>>>>
>>>>>>>>>>> Just do this next time and it should work:
>>>>>>>>>>>
>>>>>>>>>>> 1. Make sure you have a local bound dolfin branch:
>>>>>>>>>>>
>>>>>>>>>>>  bzr checkout lp:dolfin trunk
>>>>>>>>>>>
>>>>>>>>>>> 2. Merge *from* that branch, not push to it:
>>>>>>>>>>>
>>>>>>>>>>>  cd trunk
>>>>>>>>>>>  bzr merge <path to your local repo>
>>>>>>>>>>>  bzr commit -m merge
>>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> It just worked before. It was simpler, and I could work against any
>>>>>>>>>> branch, like by personal branch under dolfin-core.
>>>>>>>>>>
>>>>>>>>>
>>>>>>>>> After trying the no-revisions-removed approach for a while, I also find it significantly more cumbersome, especially with the main vs personal branches.
>>>>>>>>>
>>>>>>>>> Although I see the point, I never encountered a problem with the changing revision numbers before.
>>>>>>>>
>>>>>>>> If Garth can't be bothered, maybe you could describe a specific
>>>>>>>> example that doesn't work?
>>>>>>>>
>>>>>>>
>>>>>>> Why would I bother with something that I think is pointless and
>>>>>>> cumbersome? Like Marie, I have never had a problem with the present
>>>>>>> approach.
>>>>>>
>>>>>> I disagree. I think there is a point to it and that it's not
>>>>>> cumbersome.
>>>>>>
>>>>>> I'm just asking for a simple example that I can try. Otherwise it's
>>>>>> just handwaving.
>>>>>>
>>>>>
>>>>> You made the change, so the onus is on you to make a case, not the other
>>>>> way around. I'm changing it back because I don't have any inclination to
>>>>> change unless someone can make a case why. The status quo rules until
>>>>> there is a consensus.
>>>>>
>>>>> What I don't want is to work in a CVS way. See:
>>>>>
>>>>>   http://wiki.bazaar.canonical.com/BzrForCVSUsers
>>>>>
>>>>> It advocates checkout for those who want to keep their CVS work flow,
>>>>> and says of the approach:
>>>>>
>>>>> "This section explains how to perform common CVS behaviours in a Bazaar
>>>>> world. Unfortunately, this means that I won't be able to teach you many
>>>>> of the things that are unique to decentralized revision control systems.
>>>>>
>>>>> This section covers how to use Bazaar in checkout mode. Reading section
>>>>> 3, which covers standard Bazaar methods, is highly encouraged."
>>>>>
>>>>> Section 3 describes what we've been doing all along.
>>>>
>>>> I think you still need to make the case that it doesn't work. I claim
>>>> it does and if you say that it fails so badly, it should be easy to
>>>> come up with a single example of where it doesn't work.
>>>>
>>>> I've already made the case for the change: to not change history of the
>>>> common branch (which append_revisions_only prevents).
>>>>
>>>
>>> Which I don't support. I also disagree with the technical point of
>>> history changes.
>>>
>>> A common branch is a centralised concept. I support developers using
>>> separate feature branches, and using personal branches on Launchpad, and
>>
>> I work that way all the time, pushing and pulling branches
>> between different computers and launchpad branches.
>>
>>> the merging this into lp:dolfin.
>>>
>>> Garth
>>
>> The only difference between the approaches is to merge
>> your work _into_ lp:dolfin instead of merging lp:dolfin into your work.
>>
>
> I can follow that for simple usage, but I'm often merging between, for
> example, lp:dolfin and lp:~dolfin-core/dolfin/wells and something in
> between.

cd work
bzr merge lp:~dolfin-core/dolfin/wells && bzr commit
bzr merge ../localfeaturebranch && bzr commit
bzr merge lp:~dolfin-core/dolfin/yetanotherfeature && bzr commit
cd ../trunk
bzr pull lp:dolfin
bzr merge ../work && bzr commit
bzr push lp:dolfin

I don't see any problem. Your offline problem was probably
the checkout vs branch issue I mentioned in the other mail.
Just unbind the trunk/ branch and there is no such problem.

>> You have educated me on the difference between revision number
>> and revision id. I thought there was no such thing after some reading.
>>
>> I have now tested the command
>>   bzr branch work -r <revision-id> oldstate
>> and it works perfectly, with revision-id being a revision
>> previously 'hidden' behind a merge.
>>
>
> I use 'bzr visualise' and it doesn't hide anything. I see the parallel
> lines that we used to have with the Mecurial web interface.
>
> On the command line
>
>  bzr log --include-merges
>
> has the same effect.
>
>> Thus, if everybody communicates unique revisions with
>> the revision id and not the revision number, there is no
>> technical difference between the approaches.
>>
>> It is still more convenient to communicate with revision numbers though...
>>


This statement is wrong:

> This will still work if one says #xxx on lp:dolfin. The bzr docs say
> that the revision numbers on given branch will never change.
>
> Garth

The revision numbers on the lp:dolfin branch _do_ change
every time you get this "2 revisions removed from branch" mail.
This it is exactly what we've been trying to avoid.

I have no problem communicating with revision ids instead of revision numbers.

Martin